It is proposed to study factors underlying the stable forms of outer segments and local regions involved in disc formation and phagosome formation. The techniques will include electron microscopic study of sections and freeze-fracture replicas of these organelles after their exposure to heat, light, and certain enzyme chemical agents. It is proposed to develop a system permitting the layer-by-layer chemical analysis of retinas following their isolation and incubation in perfusing solutions. It is proposed to further explore the role of taurine and cyclic nucleotides in the retina.